Alcohol Consumption and Body Mass Index: AlcoholFood Competition or Third-Variable Problem? Jenna R. Cummings & A. Janet Tomiyama Department of Psychology, University of California, Los Angeles § § § § § § § Alcohol-food competition framework posits that alcohol and food cannot simultaneously activate reward pathways à individuals tend to consume one substance to the exclusion of the other1. In support, studies consistently document an inverse relationship between alcohol consumption and Body Mass Index (BMI)2-4. However, this research is limited in two respects: 1. The inverse relationship has only been documented cross-sectionally. 2. In these studies BMI is used as a proxy for actual caloric intake. The current study examined the longitudinal relationship of alcohol intake to both BMI and directly examined caloric intake. Data obtained via the National Heart, Lung, and Blood Institute Growth and Health Study. Sample of 2,379 Black (n = 1,213) and White (n = 1,166) adolescent girls assessed yearly from age 15 to 19. At annual visits, anthropometric and consumption behavior data was collected: 1. Alcohol intake à During the past 30 days, on how many days did you have at least one drink of alcohol? 2. Caloric intake à 3-day daily food diary recording all food and drink, excluding alcohol. 3. BMI à calculated using the standard formula (weight[kg]/height[m]2). § Measured covariates: Race, household income, parental education, and age of menarche. Age 16 Age 17 Age 17 Age 18 Alcohol Consumption Age 19 Alcohol Consumption Age 19 -0.10** Alcohol Consumption Age 15 Alcohol Consumption Age 16 BMI Age 19 -0.05 -0.06* -0.11 0.11 0.07 Total Food Consumption Age 16 BMI Age 15 Age 16 Age 17 Age 18 CFI = 0.92, RMSEA = 0.10 Total Food Consumption Age 19 Age 17 CFI = 0.97, RMSEA = 0.04 Multivariate growth models between alcohol intake and BMI, and alcohol and caloric intake. Covariance pathways within these variables’ intercepts and slopes represented by gold lines. Longitudinal relationships between study variable represented by blue lines. Alcohol intake and BMI increased at mean-level over five years, but caloric intake remained stable. This is illustrated by steep versus flat arrows. Standardized values reported. CFI = Comparative Fit Index, RMSEA = Root Mean Square Error of Approximation. * p < .05, ** p < .01, *** p < .001. § Alcohol Intake and BMI: § § § Alcohol Intake and Caloric Intake: § § § § The estimates of slope for alcohol consumption and BMI were significantly negatively associated. Further, a significant negative prospective association between the estimates of intercept for BMI and slope for alcohol intake emerged. The estimates of slope for alcohol consumption and total calories and sugar consumption were not significantly associated. Neither were prospective relationships between intercepts and slopes. BMI, in this context, is not an appropriate proxy for caloric intake. Rather than alcohol-food competition within an individual, third variables are likely driving the inverse relationship between alcohol intake and BMI. § Future work can examine alternative explanations: 1. Metabolism could confer an individual with both a lean BMI and higher tolerance to alcohol. 2. Given that individuals commonly drink alcohol as a part of social functions, those with higher BMIs may experience weight discrimination and be less likely to attend social functions and drink alcohol. References: 1Gearhardt, & Corbin (2009). Body mass index and alcohol consumption: Family history of alcoholism as a moderator. Psychology of Addictive Behaviors, 23(2), 216–25. 2Colditz, Giovannucci, Rimm, Stampfer, Rosner, Speizer, Willett (1991). Alcohol intake in relation to diet and obesity in women and men. The American Journal of Clinical Nutrition, 54(1), 49–55. 3Gearhardt, Harrison, & McKee (2012). Does co-morbid depression alter the inverse relationship between obesity and substance use disorders? Drug and Alcohol Dependence, 124(1-2), 185–8. 4Kleiner, Gold, Frost-Pineda, Lenz-Brunsman, Perri, & Jacobs (2004). Body mass index and alcohol use. Journal of Addictive Diseases, 105–118.